Increase of light extraction from GaN based light emitting diodes incorporating patterned structure by colloidal lithography

The light extraction efficiency of light emitting diodes (LEDs) was enhanced by incorporating nanoscale patterns inside the LED structure. A hole patterned p-GaN layer and a pillar patterned indium-tin-oxide (ITO) contact layer were fabricated by using colloidal lithography with size-tunable polystyrene spheres. It was found that the light output power (at 20mA) of the LEDs with the hole patterned p-GaN layer and the pillar patterned ITO contact layer were enhanced by 21% and 10%, respectively, compared with the conventional LED due to the increase of the extraction probability of the internally reflected photons through the patterns.